# Copyright 1999-2020 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

import os
import warnings

import portage
from portage.const import VDB_PATH
from portage.dbapi.vartree import vartree
from portage.dep._slot_operator import find_built_slot_operator_atoms
from portage.eapi import _get_eapi_attrs
from portage.exception import InvalidData, InvalidDependString
from portage.update import grab_updates, parse_updates, update_dbentries
from portage.versions import _pkg_str

from _emerge.Package import Package
from _emerge.PackageVirtualDbapi import PackageVirtualDbapi
from _emerge.resolver.DbapiProvidesIndex import PackageDbapiProvidesIndex


class FakeVardbGetPath:
    """
    Implements the vardbapi.getpath() method which is used in error handling
    code for the Package class and vartree.get_provide().
    """

    def __init__(self, vardb):
        self.settings = vardb.settings

    def __call__(self, cpv, filename=None):
        path = os.path.join(self.settings["EROOT"], VDB_PATH, cpv)
        if filename is not None:
            path = os.path.join(path, filename)
        return path


class _DynamicDepsNotApplicable(Exception):
    pass


class FakeVartree(vartree):
    """This is implements an in-memory copy of a vartree instance that provides
    all the interfaces required for use by the depgraph.  The vardb is locked
    during the constructor call just long enough to read a copy of the
    installed package information.  This allows the depgraph to do it's
    dependency calculations without holding a lock on the vardb.  It also
    allows things like vardb global updates to be done in memory so that the
    user doesn't necessarily need write access to the vardb in cases where
    global updates are necessary (updates are performed when necessary if there
    is not a matching ebuild in the tree). Instances of this class are not
    populated until the sync() method is called."""

    def __init__(
        self,
        root_config,
        pkg_cache=None,
        pkg_root_config=None,
        dynamic_deps=False,
        ignore_built_slot_operator_deps=False,
        soname_deps=False,
    ):
        self._root_config = root_config
        self._dynamic_deps = dynamic_deps
        self._ignore_built_slot_operator_deps = ignore_built_slot_operator_deps
        if pkg_root_config is None:
            pkg_root_config = self._root_config
        self._pkg_root_config = pkg_root_config
        if pkg_cache is None:
            pkg_cache = {}
        real_vartree = root_config.trees["vartree"]
        self._real_vardb = real_vartree.dbapi
        portdb = root_config.trees["porttree"].dbapi
        self.settings = real_vartree.settings
        mykeys = list(real_vartree.dbapi._aux_cache_keys)
        if "_mtime_" not in mykeys:
            mykeys.append("_mtime_")
        self._db_keys = mykeys
        self._pkg_cache = pkg_cache
        self.dbapi = PackageVirtualDbapi(real_vartree.settings)
        if soname_deps:
            self.dbapi = PackageDbapiProvidesIndex(self.dbapi)
        self.dbapi.getpath = FakeVardbGetPath(self.dbapi)
        self.dbapi._aux_cache_keys = set(self._db_keys)

        # Initialize variables needed for lazy cache pulls of the live ebuild
        # metadata.  This ensures that the vardb lock is released ASAP, without
        # being delayed in case cache generation is triggered.
        self._aux_get = self.dbapi.aux_get
        self._match = self.dbapi.match
        if dynamic_deps:
            self.dbapi.aux_get = self._aux_get_wrapper
            self.dbapi.match = self._match_wrapper
        self._aux_get_history = set()
        self._portdb_keys = Package._dep_keys + ("EAPI", "KEYWORDS")
        self._portdb = portdb
        self._global_updates = None

    @property
    def root(self):
        warnings.warn(
            "The root attribute of "
            "_emerge.FakeVartree.FakeVartree"
            " is deprecated. Use "
            "settings['ROOT'] instead.",
            DeprecationWarning,
            stacklevel=3,
        )
        return self.settings["ROOT"]

    def _match_wrapper(self, cpv, use_cache=1):
        """
        Make sure the metadata in Package instances gets updated for any
        cpv that is returned from a match() call, since the metadata can
        be accessed directly from the Package instance instead of via
        aux_get().
        """
        matches = self._match(cpv, use_cache=use_cache)
        for cpv in matches:
            if cpv in self._aux_get_history:
                continue
            self._aux_get_wrapper(cpv, [])
        return matches

    def _aux_get_wrapper(self, cpv, wants, myrepo=None):
        if cpv in self._aux_get_history:
            return self._aux_get(cpv, wants)
        self._aux_get_history.add(cpv)

        # This raises a KeyError to the caller if appropriate.
        pkg = self.dbapi._cpv_map[cpv]

        try:
            live_metadata = dict(
                zip(
                    self._portdb_keys,
                    self._portdb.aux_get(cpv, self._portdb_keys, myrepo=pkg.repo),
                )
            )
        except (KeyError, portage.exception.PortageException):
            live_metadata = None

        self._apply_dynamic_deps(pkg, live_metadata)

        return self._aux_get(cpv, wants)

    def _apply_dynamic_deps(self, pkg, live_metadata):
        try:
            if live_metadata is None:
                raise _DynamicDepsNotApplicable()
            # Use the metadata from the installed instance if the EAPI
            # of either instance is unsupported, since if the installed
            # instance has an unsupported or corrupt EAPI then we don't
            # want to attempt to do complex operations such as execute
            # pkg_config, pkg_prerm or pkg_postrm phases. If both EAPIs
            # are supported then go ahead and use the live_metadata, in
            # order to respect dep updates without revision bump or EAPI
            # bump, as in bug #368725.
            if not (
                portage.eapi_is_supported(live_metadata["EAPI"])
                and portage.eapi_is_supported(pkg.eapi)
            ):
                raise _DynamicDepsNotApplicable()

            # preserve built slot/sub-slot := operator deps
            built_slot_operator_atoms = None
            if (
                not self._ignore_built_slot_operator_deps
                and _get_eapi_attrs(pkg.eapi).slot_operator
            ):
                try:
                    built_slot_operator_atoms = find_built_slot_operator_atoms(pkg)
                except InvalidDependString:
                    pass

            if built_slot_operator_atoms:
                live_eapi_attrs = _get_eapi_attrs(live_metadata["EAPI"])
                if not live_eapi_attrs.slot_operator:
                    raise _DynamicDepsNotApplicable()
                for k, v in built_slot_operator_atoms.items():
                    live_metadata[k] += " " + " ".join(str(atom) for atom in v)

            self.dbapi.aux_update(pkg.cpv, live_metadata)
        except _DynamicDepsNotApplicable:
            if self._global_updates is None:
                self._global_updates = grab_global_updates(self._portdb)

            # Bypass _aux_get_wrapper, since calling that
            # here would trigger infinite recursion.
            aux_keys = Package._dep_keys + self.dbapi._pkg_str_aux_keys
            aux_dict = dict(zip(aux_keys, self._aux_get(pkg.cpv, aux_keys)))
            perform_global_updates(pkg.cpv, aux_dict, self.dbapi, self._global_updates)

    def dynamic_deps_applied(self, pkg):
        """True if the dynamic-deps apply has already run for ``pkg`` on this
        instance.

        depgraph._load_vdb() runs once per depgraph, but the FakeVartree lives
        in frozen_config and is therefore shared by every backtracking depgraph.
        The preload must not run twice over the same instance: the first pass
        rewrites Package._metadata via aux_update(), so a second pass would be
        deriving live dependencies for metadata that is no longer the vdb's."""
        return pkg.cpv in self._aux_get_history

    def dynamic_deps_preload(self, pkg, metadata):
        if metadata is not None:
            metadata = {k: metadata.get(k, "") for k in self._portdb_keys}
        self._apply_dynamic_deps(pkg, metadata)
        self._aux_get_history.add(pkg.cpv)

    def cpv_discard(self, pkg):
        """
        Discard a package from the fake vardb if it exists.
        """
        old_pkg = self.dbapi.get(pkg)
        if old_pkg is not None:
            self.dbapi.cpv_remove(old_pkg)
            self._pkg_cache.pop(old_pkg, None)
            self._aux_get_history.discard(old_pkg.cpv)

    def sync(self, acquire_lock=1):
        """
        Call this method to synchronize state with the real vardb
        after one or more packages may have been installed or
        uninstalled.
        """
        locked = False
        try:
            if acquire_lock and os.access(self._real_vardb._dbroot, os.W_OK):
                self._real_vardb.lock()
                locked = True
            self._sync()
        finally:
            if locked:
                self._real_vardb.unlock()

        # Populate the old-style virtuals using the cached values.
        # Skip the aux_get wrapper here, to avoid unwanted
        # cache generation.
        try:
            self.dbapi.aux_get = self._aux_get
            self.settings._populate_treeVirtuals_if_needed(self)
        finally:
            if self._dynamic_deps:
                self.dbapi.aux_get = self._aux_get_wrapper

    def _sync(self):
        real_vardb = self._root_config.trees["vartree"].dbapi
        current_cpv_set = frozenset(real_vardb.cpv_all())
        pkg_vardb = self.dbapi

        # Remove any packages that have been uninstalled.
        for pkg in list(pkg_vardb):
            if pkg.cpv not in current_cpv_set:
                self.cpv_discard(pkg)

        # Validate counters and timestamps.
        slot_counters = {}
        root_config = self._pkg_root_config
        validation_keys = ["COUNTER", "_mtime_"]
        for cpv in current_cpv_set:
            pkg_hash_key = Package._gen_hash_key(
                cpv=cpv, installed=True, root_config=root_config, type_name="installed"
            )
            pkg = pkg_vardb.get(pkg_hash_key)
            if pkg is not None:
                counter, mtime = real_vardb.aux_get(cpv, validation_keys)
                try:
                    counter = int(counter)
                except ValueError:
                    counter = 0

                if counter != pkg.counter or mtime != pkg.mtime:
                    self.cpv_discard(pkg)
                    pkg = None

            if pkg is None:
                pkg = self._pkg(cpv)

            other_counter = slot_counters.get(pkg.slot_atom)
            if other_counter is not None:
                if other_counter > pkg.counter:
                    continue

            slot_counters[pkg.slot_atom] = pkg.counter
            pkg_vardb.cpv_inject(pkg)

    def _pkg(self, cpv):
        """
        The RootConfig instance that will become the Package.root_config
        attribute can be overridden by the FakeVartree pkg_root_config
        constructory argument, since we want to be consistent with the
        depgraph._pkg() method which uses a specially optimized
        RootConfig that has a FakeVartree instead of a real vartree.
        """
        pkg = Package(
            cpv=cpv,
            built=True,
            installed=True,
            metadata=zip(self._db_keys, self._real_vardb.aux_get(cpv, self._db_keys)),
            root_config=self._pkg_root_config,
            type_name="installed",
        )

        self._pkg_cache[pkg] = pkg
        return pkg


def grab_global_updates(portdb):
    retupdates = {}

    for repo_name in portdb.getRepositories():
        repo = portdb.getRepositoryPath(repo_name)
        updpath = os.path.join(repo, "profiles", "updates")
        if not os.path.isdir(updpath):
            continue

        try:
            rawupdates = grab_updates(updpath)
        except portage.exception.DirectoryNotFound:
            rawupdates = []
        upd_commands = []
        for mykey, mystat, mycontent in rawupdates:
            commands, errors = parse_updates(mycontent)
            upd_commands.extend(commands)
        retupdates[repo_name] = upd_commands

    master_repo = portdb.repositories.mainRepo()
    if master_repo is not None:
        master_repo = master_repo.name
    if master_repo in retupdates:
        retupdates["DEFAULT"] = retupdates[master_repo]

    return retupdates


def perform_global_updates(mycpv, aux_dict, mydb, myupdates):
    try:
        pkg = _pkg_str(mycpv, metadata=aux_dict, settings=mydb.settings)
    except InvalidData:
        return
    aux_dict = {k: aux_dict[k] for k in Package._dep_keys}
    try:
        mycommands = myupdates[pkg.repo]
    except KeyError:
        try:
            mycommands = myupdates["DEFAULT"]
        except KeyError:
            return

    if not mycommands:
        return

    updates = update_dbentries(mycommands, aux_dict, parent=pkg)
    if updates:
        mydb.aux_update(mycpv, updates)
